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Fig. 2. The adsorption of 2-ketogluconate (kG) by gibbsite and kaolinite as a function of pH and ionic strength. In (a), the symbols represent experimentally determined kG adsorption and the solid lines represent the 1-pK basic Stern optimized fit to the experimental data using the chemical models described in Tables 2, 3, and 4. The dashed lines represent the model-predicted adsorption of kG by kaolinite using the surface complexation model developed for kG adsorption by gibbsite. The dotted lines represent the model-predicted adsorption of kG by gibbsite using the 
AlOH–1kG–1.5(s) species rather than the Al2O2H–1kG–(s) species. Graph (b) illustrates model-predicted adsorbed kG species composition as a fraction of the total predicted adsorbed kG for gibbsite (filled symbols) and kaolinite (open symbols).
